[Federal Register Volume 62, Number 17 (Monday, January 27, 1997)]
[Rules and Regulations]
[Pages 3781-3784]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-1438]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-01-AD; Amendment 39-9895; AD 97-02-10]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, 
and C-9 (Military) Series Airplanes, Model MD-88 Airplanes, and Model 
MD-90 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain McDonnell Douglas Model DC-9, DC-9-80, and C-9 
(military) series airplanes, Model MD-88 airplanes, and Model MD-90 
airplanes. This action requires a visual check to determine the part 
and serial numbers of the upper lock link assembly of the nose landing 
gear (NLG); repetitive inspections of certain upper lock link 
assemblies to detect fatigue cracking; and modification of the NLG. 
This action also provides for terminating action for the repetitive 
inspections. This amendment is prompted by a report indicating that, 
due to fatigue cracking, the upper lock link assembly on an airplane 
fractured, and consequently prevented the NLG from extending fully. The 
actions specified in this AD are intended to prevent this assembly from 
fracturing due to fatigue cracking, and the NLG consequently failing to 
extend fully; this condition could result in injury to passengers and 
flight crew, and damage to the airplane.

DATES: Effective February 11, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 11, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before March 28, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-01-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    The service information referenced in this AD may be obtained from 
McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach,

[[Page 3782]]

California 90846, Attention: Technical Publications Business 
Administration, Department C1-L51 (2-60). This information may be 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, 
Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Brent Bandley, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone 
(310) 627-5237; fax (310) 627-5210.

SUPPLEMENTARY INFORMATION: The FAA has recently received a report 
indicating that the upper lock link assembly of the nose landing gear 
(NLG) on a McDonnell Douglas DC-9-80 series airplane failed prior to 
landing. As a result of this failure, the airplane sustained moderate 
damage to the forward lower fuselage.
    An investigation by the operator revealed that this assembly had 
fractured and jammed against the shock strut, which prevented the NLG 
from extending fully. This fracture was caused by fatigue cracking that 
originated at the lower end of the assembly where the flange and inner 
radius meet. The operator also detected similar fatigue cracking in two 
other upper lock link assemblies during an inspection of other 
airplanes in its fleet.
    An upper lock link assembly can be either manufactured from 
aluminum plate or forged from aluminum. The three cracked assemblies 
that were detected were aluminum plate, a material which has a much 
shorter fatigue life than forged aluminum. In addition to Model DC-9-80 
series airplanes, assemblies of aluminum plate may be installed on 
Model DC-9 and C-9 (military) series airplanes, Model MD-88 airplanes, 
and Model MD-90 airplanes.
    Fracturing of the upper lock link assembly due to fatigue cracking, 
if not corrected, can result in the failure of the NLG to extend fully, 
which could lead to injury to passengers and flight crew, and damage to 
the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Alert Service 
Bulletin DC9-32A298 [for Model DC-9, DC-9-80, and C-9 (military) series 
airplanes, and Model MD-88 airplanes], and McDonnell Douglas Alert 
Service Bulletin MD90-32A019 [for Model MD-90 airplanes], both dated 
December 19, 1996. Both alert service bulletins describe procedures for 
conducting a visual check of the part number and serial number on the 
upper lock link assembly of the NLG to identify whether an assembly has 
been forged from aluminum (an ``exempt upper lock link assembly''), or 
has been manufactured from aluminum plate (a ``possible discrepant 
upper lock link assembly''). No further action is necessary if an 
exempt upper lock link assembly is installed.
    Both alert service documents also describe procedures for 
conducting repetitive high frequency eddy current inspections or Type I 
fluorescent penetrant inspections to detect fatigue cracking in a 
possible discrepant upper lock link assembly. When fatigue cracking is 
detected in this upper lock link assembly or when the assembly's safe 
life (46,500 cycles of the NLG) has been reached, the pin assembly of 
the NLG is to be replaced with a new or serviceable pin assembly. (The 
upper lock link assembly is contained within the pin assembly.) If the 
pin assembly is replaced with one that contains an exempt upper lock 
link assembly, the need for subsequent repetitive inspections and 
replacement of parts is eliminated.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other McDonnell Douglas Model DC-9, DC-9-80, and C-
9 (military) series airplanes, Model MD-88 airplanes, and Model MD-90 
airplanes, of the same type design, this AD is being issued to prevent 
fracturing of the upper lock link assembly due to fatigue cracking, and 
the consequent failure of the NLG to extend fully, which could lead to 
injury to passengers and flight crew, and damage to the airplane.
    This AD requires a visual check of the part number and serial 
number on the upper lock link assembly to identify whether this 
assembly is a possible discrepant assembly or an exempt assembly. (No 
further action is required if an upper lock link assembly is an exempt 
assembly.)
    This AD also requires repetitive high frequency eddy current 
inspections or Type I fluorescent penetrant inspections of any possible 
discrepant upper lock link assembly to detect fatigue cracking. When 
fatigue cracking is detected in the upper lock link assembly, this AD 
requires that the pin assembly of the NLG be replaced with a new or 
serviceable pin assembly. The operator, at its option, may install a 
replacement pin assembly that contains an exempt, rather than a 
possible discrepant, upper lock link; this substitution terminates the 
requirement for repetitive inspections.
    The actions are required to be accomplished in accordance with the 
applicable alert service bulletin described previously.

Interim Action

    This is considered to be interim action. The manufacturer has 
advised that it currently is developing a modification that will 
positively address the unsafe condition addressed by this AD. Once this 
modification is developed, approved, and available, the FAA may 
consider additional rulemaking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact

[[Page 3783]]

concerned with the substance of this AD will be filed in the Rules 
Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 97-NM-01-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

97-02-10  McDonnell Douglas: Amendment 39-9895. Docket 97-NM-01-AD.
    Applicability: Model DC-9, DC-9-80, and C-9 (military) series 
airplanes, Model MD-88 airplanes, and Model MD-90 airplanes; as 
listed in McDonnell Douglas Alert Service Bulletins DC9-32A298 [for 
Model DC-9, DC-9-80, and C-9 (military) series airplanes, and Model 
MD-88 airplanes], and McDonnell Douglas Alert Service Bulletin MD90-
32A019 [for Model MD-90 airplanes], both dated December 19, 1996; 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (e) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent fracturing of the upper lock link assembly of the 
nose landing gear (NLG) due to fatigue cracking, and the consequent 
failure of the NLG to extend fully, which could lead to injury to 
passengers and flight crew, and damage to the airplane, accomplish 
the following:
    (a) Prior to the accumulation of 10,000 total cycles of the NLG, 
or within 90 days after the effective date of this AD, whichever 
occurs later, conduct a visual check of the upper lock link assembly 
of the NLG to determine its part and serial number, in accordance 
with McDonnell Douglas Alert Service Bulletin DC9-32A298 [for Model 
DC-9, DC-9-80, and C-9 (military) series airplanes, and Model MD-88 
airplanes], or McDonnell Douglas Alert Service Bulletin MD90-32A019 
[for Model MD-90 airplanes], both dated December 19, 1996, as 
applicable.
    (b) If the part number and serial number of the upper lock link 
assembly are listed in paragraph (b)(1) or (b)(2) of this AD (``an 
exempt upper lock link assembly''), no further action is required.

    Note 2: An ``exempt upper lock link assembly'' as specified in 
paragraph (b) of this AD is an assembly that is manufactured of 
forged aluminum.

    (1) For Model DC-9, DC-9-80, and C-9 (military) series 
airplanes, and Model MD-88 airplanes: Part Number (P/N) 3914464-(any 
configuration) having serial numbers (S/N) HMI001 through HMI172 
inclusive, or S/N WPI1000 and subsequent; or P/N 5920472-(any 
configuration) having any serial number.
    (2) For Model MD-90 airplanes: P/N 3914464-503 having S/N HMI001 
through HMI172 inclusive, or S/N WPI1000 and subsequent.
    (c) If the part number and serial number of the upper lock link 
assembly are not listed in paragraph (b)(1) or (b)(2) of this AD ( a 
``possible discrepant upper lock link assembly''), except as 
provided by paragraph (c)(3) of this AD, prior to further flight, 
conduct either a high frequency eddy current inspection or a Type I 
fluorescent penetrant inspection of this assembly to detect fatigue 
cracks, in accordance with McDonnell Douglas Alert Service Bulletin 
DC9-32A298 [for Model DC-9, DC-9-80, and C-9 (military) series 
airplanes, and Model MD-88 airplanes], or McDonnell Douglas Alert 
Service Bulletin MD90-32A019 [for Model MD-90 airplanes], both dated 
December 19, 1996.

    Note 3: A ``possible discrepant upper lock link assembly'' as 
specified in paragraph (c) of this AD is an assembly that may be 
manufactured from aluminum plate.

    (1) If no crack is detected, repeat either type of inspection 
required by paragraph (c) of this AD at intervals not to exceed 
5,000 cycles of the NLG.
    (2) If any crack is detected, prior to further flight, replace 
the pin assembly of the NLG in accordance with the applicable alert 
service bulletin.
    (3) A Type I fluorescent penetrant inspection of the upper lock 
link assembly that has been conducted within the last 12 months 
prior to the effective date of this AD and in accordance with the 
DC-9 Overhaul Manual or MD-90 Component Manual, Chapter 20-70-2, is 
considered acceptable for compliance with the initial inspection 
required by paragraph (c) of this AD. If no crack was detected 
during that inspection, subsequent repetitive inspections are 
required to be accomplished at the intervals specified in paragraph 
(c)(1) of this AD.
    (d) When replacement of the pin assembly of the NLG is required 
in accordance with paragraph (c)(1) or (c)(2) of this AD:
    (1) If the pin assembly is replaced with a new assembly that 
contains a possible discrepant upper lock assembly: After the pin 
assembly has been replaced, repeat the inspection required by 
paragraph (c) of this AD prior to the accumulation of 10,000 cycles 
of the NLG.
    (2) If the pin assembly is replaced with a serviceable assembly 
that contains a possible discrepant upper lock assembly: After the 
pin assembly has been replaced, repeat the inspection required by 
paragraph (c) of this AD either prior to the accumulation of 10,000 
total cycles of the NLG for that pin assembly, or prior to further 
flight, whichever occurs later.
    (3) If the pin assembly is replaced with a pin assembly that 
contains an exempt upper lock link assembly: No further action is 
required. This installation constitutes terminating action for the 
repetitive inspections required by this AD.
    (e) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Los Angeles Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through

[[Page 3784]]

an appropriate FAA Principal Maintenance Inspector, who may add 
comments and then send it to the Manager, Los Angeles ACO.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (f) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (g) The visual check, repetitive inspections, and replacement of 
the pin assembly of the NLG shall be done in accordance with 
McDonnell Douglas Alert Service Bulletin DC9-32A298, dated December 
19, 1996; or McDonnell Douglas Alert Service Bulletin MD90-32A019, 
dated December 19, 1996; as applicable. This incorporation by 
reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
obtained from McDonnell Douglas Corporation, 3855 Lakewood 
Boulevard, Long Beach, California 90846, Attention: Technical 
Publications Business Administration, Department C1-L51 (2-60). 
Copies may be inspected at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport 
Airplane Directorate, Los Angeles Aircraft Certification Office, 
3960 Paramount Boulevard, Lakewood, California; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.
    (h) This amendment becomes effective on February 11, 1997.

    Issued in Renton, Washington, on January 14, 1997.
S. R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-1438 Filed 1-24-97; 8:45 am]
BILLING CODE 4910-13-P